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MLAB 1415- Hematology
Keri Brophy-Martinez
Chapter 7: Leukocytes
Terms

Myelopoiesis - the production and
development of myeloid cells in the
bone marrow
Leukocytes

Function

Protect the host from infectious agents
or pathogens

Innate=Natural Immune response



1st response to pathogens (nonself)
Always available
Adaptive Immune response




Starts in lymphoid tissue
Slow
Long-lasting immunity (memory)
Lymphocytes become “activated”
Differentiation & Maturation
1.
2.
3.
Leukocytes develop from HSC
(hematopoietic stem cell)
Common Myeloid progenitor (CMP)
cell gives rise to the committed
precursor cells for the neutrophilic,
eosinophilic, basophilic and
monocytic lineages.
Once lineage commitment has
occurred, maturation begins.
Maturation Changes




Nucleoli disappear
Chromatin condenses
Nuclear mass indents and segments
Cytoplasm becomes granular &
pinkens
Neutrophil Lifespan

Three areas

Bone marrow


Peripheral blood


Differentiation, proliferation, maturation
Circulate for a few hours
Tissues

Work in host defense
Regulation

Neutrophil production primarily
regulated by cytokines



Interleukin-3
Granulocyte -monocyte-colony
stimulating factor (GM-CSF)
Granulocyte-colony-stimulating factor
(G-CSF)
Maturation of the granulocytic series
**Least mature to mature**

Myeloblast


Size: 14-20µm
Cytoplasm



Nucleus





Slight
amount/blue
No granules
((possible Auer
rods to be
discussed in
another
section)
Round/Central
or eccentric
Reddish purple
1-3 nucleoli
Fine
meshlike/lacy
chromatin with
no clumping
N:C ratio = 4:1
Maturation of the granulocytic series

Promyelocyte
(progranulocyte)




Size: 15-21 µm
Cytoplasm
 Increased amount/blue
 Fine, azurophilic,
nonspecific granules
present
Nucleus
 Round/Central or
eccentric
 Reddish-purple
 Fine, meshlike/lacy
chromatin beginning to
clump
 1-2 nucleoli
N:C ratio = 3:1
Maturation of the granulocytic series

Myelocyte



Last myeloid cell capable of
division
Size: 12-18µm
Cytoplasm




Nucleus





Increased, bluish-pink
(“dawning of
neutrophilia”)
Fine azurophilic, specific
granules
Secretory vesicles
Round or oval/eccentric
Reddish-purple
Chromatin loosely
clumped
No nucleolus
N:C ratio = 2:1 or 1:1
Maturation of the granulocytic series

Metamyelocyte



Also called “meta” or
“juvenile”
Size: 10-18µm
Cytoplasm





Nucleus






Moderate amount
Specific granules
(neutrophilic, eosinophilic or
basophilic)
Tertiary granules
Secretory vesicles
Indented (kidney-bean
shaped)
Central or eccentric
Purple
Clumped chromatin
No nucleolus
N:C ratio = 1:1
Maturation of the granulocytic series

Band



1st stage found in P.B
Size: 9-15µm
Cytoplasm



Moderate amount
Specific granules
(see meta)
Nucleus



Elongated, narrow
band (sausage)
shape with uniform
thickness
Central or eccentric
Clumped, coarsely
granular chromatin
Maturation of the granulocytic series

Segmented neutrophil, eosinophil or basophil


Size: 10-16µm
Cytoplasm

Neutrophil - Granules stain equally with eosin and methylene
blue, causing a pinkish appearance


Eosinophil - Granules stain mainly red, due to reaction with
eosin in stain



Nucleus



Normal in circulation = 0-5%
Basophil - Granules stain mainlyblue, due to the reaction with
methylene blue in stain


Normal in circulation = 40 - 80%
Normal in circulation = 0-1%
Mast cell is a tissue basophil
Neutrophil - purplish-red, clumped granular chromatin, 2-5
distinct nuclear lobes connected by a filament of chromatin
Eosinophil - deep blue purple, coarsely granular chromatin, 2
distinct lobes
Basophil - deep blue purple, coarsely granular chromatin, 2
nuclear lobes (sometimes obscured by cytoplasmic granules)
Maturation of the granulocytic series
Basophil
Eosinophil
Function of the granulocytic series

Neutrophils


Eosinophils




Defense against bacterial infections
Regulate inflammation
Respond to antigenic stimulation in chronic
allergies
Interact with larval stages of some helminthic
parasites
Basophils


Histamine in granules plays a role in acute,
systemic allergic reactions (sudden release of
histamine can cause anaphylactic shock)
Granules also contain heparin
Granulocytes

Why are they called granulocytes?

The granules are lysosomes created by lipids that
contain hydrolytic enzymes such as peroxidase,
acid phosphatase, lysozyme and specific
esterase.
MONOCYTES

Monopoiesis - the production and
development of monocytes,
macrophages and their precursors.
Monocytes are produced in the bone
marrow.
MONOCYTES

Function



Protect the host from infectious agents
or pathogens via innate and adaptive
immune response
Phagocytosis
Scavengers
MONOCYTES

Differentiation & maturation



Lifespan



Produced from CFU-GM
Can further differentiate into macrophages in the
tissues
P.B ~ 8 hours
Tissue
Regulation

Production primarily regulated by cytokines



GM-CSF
IL-3
M-CSF
Maturation of the monocytic series

Monoblast


Size: 12-20µm
Cytoplasm



Nucleus







Blue, moderate
amount
No granules
Round, oval or
slightly folded
Eccentric
Reddish-purple
Chromatin fine and
lacy
Vacuoles may be
present
1-2 nucleoli
N:C ratio = 4:1
Maturation of the monocytic series

Promonocyte (difficult to discern)


Size: 12-20µm
Cytoplasm





Nucleus





Paler gray-blue and abundant
“Bleb-like” pseudopods at periphery
May contain fine red “dust-like” particles,
azurophilic granules
Vacuoles may be present
Round with chromatin creases or brain-like folding
Central
Reddish-purple with light clumping of chromatin
0-2 nucleoli
N:C ratio = 3:1 or 2:1
Promonocyte
Maturation of the monocytic series

Mature monocyte



Normal in circulation: 2-9%
Size: 12-20µm
Cytoplasm





Nucleus





Pale gray-blue and abundant
Bleb-like pseudopods at periphery, variable shape
Numerous fine pale red dustlike granule scattered
throughout
Vacuoles common
Increased folding or elongated
Central
Purplish with finer clumped chromatin
No nucleoli
N:C ratio = 2:1 or 1:1
Monocyte
Macrophages

Once the monocyte enters the tissues, it becomes a macrophage




Size:15-80µm
Cytoplasm
 Gray-blue and abundant
 Ragged edges
 Vacuoles common
Nucleus
 Round with netlike appearance
 Purplish with finer clumped chromatin

Nucleoli appear
Macrophage alias’





Histiocytes in the loose connective tissue
Kupffer cells in the liver
Osteoclasts in the bone
Microglial cells in the nervous system
Also scattered throughout the body in all organ tissues (spleen, lung,
abdomen, etc.) One monocytes have grown into macrophages, they do not
normally reenter the bloodstream except in cases of inflammation
Macrophage
Lymphocytes
Differentiation & Maturation


Develop from HSC (hematopoietic stem cell)
Common Myeloid progenitor (CMP) cell and
Common lymphoid progenitor cell (CLP) gives rise
to the committed precursor cells:

T lymphocytes (60-80% of lymph population)


B lymphocytes (10-20%)


thymus
Bone marrow
Natural killer cells
Lifespan

Primary lymphoid tissue


Bone marrow
Secondary lymphoid tissue


Lymph node, spleen, Peyer’s patches in
intestine and mucosal tissues such as tonsils
Active immune response occurs in above
tissues where lymphs communicate and
interact with antigen-presenting cells,
phagocytes and macrophages
LYMPHOCYTES: T cells

Function


Cellular immune response (they do not produce antibodies)
Three subsets
 Helper T cells
 Instrumental in aiding B cells in antibody production
 Suppressor T cells
 Act as a “thermostat” to shut off the system or keep it
under control
 Cytotoxic T cells




Destroy by lysis of target cells (such as tumor cells)
Play a role in inflammatory response
Host defense when stimulated by interferon against certain viruses
(cytomegalovirus - CM, and hepatitis) by killing the virally infected
target cell before the virus replicates
Responsible for chronic organ graft rejection. (T cells have many
unique antigens on their cell surfaces, some of which are the HLA
- human lymphocyte antigen - markers. HLA markers are
instrumental in chronic graft rejection and that is why tissue
typing is done to establish a good donor match.)
LYMPHOCYTES: B cells

Function
Humoral immune response by
transforming into antibody-producing
plasma cells
 Defense against encapsulated bacteria
such as Streptococci
 Mediate hyperacute organ rejection

Lymphocytes: NK cells

Function


Recognize and kill tumor cells
Recognize and kill cells infected with a
virus
Maturation sequence of lymphocytes

Lymphoblast


Cell size: 10-18µm
Cytoplasm



Nucleus





Blue/scanty
No granules, Auer
rods are never
present
Purple, smooth
chromatin
Smudged
Round, central or
eccentric
1-2 nucleoli
N:C ratio = 4:1
Maturation sequence of lymphocytes

Prolymphocyte
(difficult to distinguish)


Size: 9-18µm
Cytoplasm



Nucleus




Blue, scanty
Usually granules are
absent, but a few
azurophilic granules
may be present
Purple, condensed
chromatin
Round or indented,
eccentric
0-1 nucleoli
N:C ratio = 3:1
Maturation sequence of lymphocytes

Mature lymphocyte


Normal adult value: 2535%
 Cell size: 7-10µm (a
typical normal lymph
has a nucleus that is
the size of a normal
RBC)
Cytoplasm



Light blue, scanty to
moderate
Few azurophilic granules
may be present
Nucleus



Purple, dense, clumped
chromatin
Round or indented,
eccentric
No nucleoli
Large lymphocytes versus monocytes

Size



Nucleus



Large lymph: clumped, condensed
Mono: lacy, brainlike folds
Granules



Large lymph: 12-15µm
Mono: 15-18µm
Large lymph: large azurophilic, easy to count
Mono: red, fine
Cytoplasm


Large lymph: clear, nongranular, may be indented by red cells
Mono: “ground glass” appearance, projection of blunt pseudopod blebs
Maturation sequence of lymphocytes

Variant lymphs


Other terms used are reactive, atypical, activated,
Downey cell, transformed, virocyte, plasmacytoid
Can be T or B cells


Caused by antigenic stimulants such as viruses,
post-transfusion reactions and organ transplants
General characteristics







Increased size due to DNA activity in the nucleus and
RNA activity in the cytoplasm
Enlarged and/or monocytoid nucleus
Variation in nuclear chromatin pattern
Nucleus may contain 1-3 nucleoli
Abundant, sometimes foamy or vacuolated cytoplasm
Variation in cytoplasmic color - gray-blue to intense blue
Absence of granules in cytoplasm
Reactive lymphocyte
Plasma cells

Plasma cells




Function is the synthesis and excretion of antibodies
(immunoglobulins)
Normally not present in the peripheral blood; comprise 2% of
bone marrow cells. (May be seen in the peripheral blood in the
disease called multiple myeloma, a disease of uncontrolled
production of immunoglobulins.)
End stage of the B lymphocyte
Appearance




Size: 10-18µm
Cytoplasm is dark blue with perinuclear halo and may contain vacuoles
indicating antibody synthesis
Nucleus is round, eccentric, dark purple with dense clumped chromatin
Variant plasma cells


Grape or Mott cell - cytoplasm completely filled with red, pink or
colorless globules called Russell bodies
Flame cell - cytoplasm stains bright red-staining proteinaceous
material
Plasma cells